As lipase-producing microorganisms, there have been known genus Pseudomonas, genus Alcaligenes, genus Mucor, genus Candida, genus Humicola, genus Rhizomucor and the like. Genes have been isolated from some of them, and a great number of lipase genes have been isolated from microorganisms of the genus Pseudomonas, in particular. Currently known such lipase genes include those from Pseudomonas fragi (Japanese Patent Laid-open Nos. Sho 62-228279 and Hei 2-190188), Pseudomonas cepacia (Japanese Patent Laid-open Nos. Hei 3-47079 and Hei 3-87187), Pseudomonas putida (EP 268 452), Pseudomonas pseudoalcaligenes (Japanese Patent Laid-open No. Hei 3-500845), Pseudomonas aeruginosa (EP 334 462), Pseudomonas glumae (Appl. Envir. Microbiol. (1992), 3738-3791), and Pseudomonas fluorescens (Appl. Envir. Microbiol. (1992) 58, 1776-1779).
It has been known that a protein encoded by a gene region downstream the lipase structural gene is involved in the lipase production in some bacteria of the genus Pseudomonas. For lipase production in Pseudomonas cepacia, the gene in the downstream region is essential, irrespective of the species of a host bacterium (EP 331 376). It has been known also that irrespective of the species of a host bacterium, the protein with an effect of stabilizing lipase is encoded by the region in the lipase produced from Pseudomonas glumae (EP 464 922).
Alternatively, a homologous host-vector system of Pseudomonas pseudoalcaligenes exerts an effect of elevating lipase production, but the gene in the downstream region is not essential for lipase production in a heterologus host-vector system thereof (EP 334 462). Furthermore, the gene in the downstream region is not present in Pseudomonas fragi.
It has been known conventionally that the washing effect of a detergent can be elevated when the detergent is blended with a lipase to degrade and remove the lipid attached to articles to be washed. The use is described in H. Andree, et. al., "Lipase as Detergent Components", Journal of Applied Biochemistry, 2, 218-229 (1980) and the like.
Preferably, a lipase to be blended with detergents can satisfactorily exert its lipase activity in a detergent solution. Under routine washing conditions, the pH of washing solutions reside in an alkaline region, so a lipase functioning at an alkaline pH is demanded. Additionally, it has been known that lipid stain is relatively readily removed generally under high temperature and high alkaline conditions but cannot sufficiently be removed through washing at low temperatures (at 60 or less). Not only in Japan where washing has conventionally been carried out at low temperatures, but also in European countries and USA, the washing temperature is likely lowered. Thus, preferably, a lipase to be blended in detergents should satisfactorily function even at low temperatures. Additionally, it is preferable that the lipase to be blended into detergents should sufficiently exhibit its functions during washing even in the presence of detergent components such as surfactant, and protease or bleach contained in many of detergents. Furthermore, preferably, the lipase to be blended into detergents should be stable in the concurrent presence of components contained in the detergents even when the lipase is stored in a blended state in the detergents.
As lipase-producing microorganisms, there have been known the genus Pseudomonas, the genus Alcaligenes, the genus Achromobacter, the genus Mucor, the genus Candida, the genus Humicola, the genus Rhizomucor and the like. Because most of the lipases from these bacterial strains have an optimum pH in a neutral to mild alkaline region, the lipases cannot work sufficiently in alkaline detergent solutions or are poorly stable therein. Still furthermore, the individual lipases from the genus Achromobacter, the genus Mucor, the genus Candida, and the genus Humicola are strongly inhibited of their activities in the presence of anionic surfactants.
Lipase-producing bacteria of the genus Pseudomonas include Pseudomonas fragi, Pseudomonas cepacia, Pseudomonas pseudoalcaligenes, Pseudomonas aeruginosa, and Pseudomonas fluorescens, but known enzymes having been isolated from these bacterial strains cannot satisfy the properties described above.